The present invention relates generally to the field of music, more specifically to playing or tuning musical instruments or singing music, and more specifically still to changing (i.e. transposing) musical scores or instrument tunings from one key to another.
Transposing a musical score involves shifting all the notes in the score up or down one or more half steps on the twelve-tone chromatic scale. This is done most often to allow a singer to sing a song that was not written in his or her vocal range. It is also often done to allow a musician to play a song in a key in which he or she is more proficient on a particular musical instrument, or to play an instrument in which the musical tone designated "A" does not correspond to the standard "A" frequency of 440 Hz. Transposing can be done mentally by counting up or down from each note a given number of half-steps, by mechanical slide rules that shift two chromatic scales opposite one another, or by electronic or digital devices in which one key is the input and the transposed values are the output. The present invention is of the mechanical slide variety of transposers.
In a twelve-tone circular reed pitch instrument, each of the twelve tones of the chromatic scale from middle C upward through B can be played by blowing air through any of twelve openings on the periphery of a circular array. In a thirteen-tone reed pitch instrument, an additional high C note is added after B as a convenience. These pitch instruments typically take the form of a small wheel held together by a screw through an axial hole.
The note values on a circular pitch instrument are typically printed or embossed as indicia on one face of the wheel next to each peripheral opening at some arbitrary radius from the center.